On Earth, the bottoms of these cracks can house organisms in...

On Earth, the bottoms of these cracks can house organisms in a much more pleasant environment than the surface at large. Obviously, if such communities thrive or thrived on Mars, some of the evidence may well be at the bottom of these cracks. We have much imaging evidence of these terrains on Mars for comparison to the similar terrains here on Earth, not just at the poles but many other high latitude and high altitude places.